How Infectious Diseases Spread across the Globe during Disasters


By Barry C. Fox, M.D.University of Wisconsin

Infectious diseases have been known to dramatically affect the outcomes of wars throughout centuries. One classical example of this phenomenon was during Napoleon’s campaign against the Russians in 1812. This story demonstrates the ability of a tiny, wingless insect, the body louse, to cause disease and infiltrate a large group of people swiftly and efficiently, with devastating results.

Image of a chewing louse.
“Body Louse” took down a notable portion of Napoleon’s army. (Image: Svetoslav Radkov/Shutterstock)

If Only They Listened to Napoleon

Starting with half a million troops, he set out to conquer Europe, then invade Russia. Napoleon was fastidious about sanitation and ensured that his troops followed his lead. However, his troops disobeyed his orders to resist fraternizing with the local population in Poland, where many citizens were suffering from typhus, as well as living in filthy conditions with disease-spreading lice.

Typhus made its way back to his camp, where tens of thousands of French soldiers died during the first month. Despite sickness and starvation, Moscow was captured in 1812, but only half of his original troops were still alive. By the time the army made their way back to France, only 7000 of his original troops remained.

Some remains of Napoleon’s army were found in 2001 in trenches in Lithuania, where 30 percent of the remains showed evidence of both typhus and another louse-borne disease known as trench fever. Typhus caused a similar problem with troops in Europe from all countries during the First World War.

This is a transcript from the video series An Introduction to Infectious Diseases. Watch it now, on Wondrium.

Where is a Vaccine When You Need One?

Let’s consider the situation in Syria during 2013 and the devastating effects of Syria’s civil war on the health of its population and its neighboring countries. The date was November 2013, and the World Health Organization, or WHO, has confirmed a polio outbreak in Syria. Syria had been free from polio since 1999. 

Image of a polio vaccine.
Because of the war, many Syrians didn’t have access to polio vaccines. (Image: Bernard Chantal/Shutterstock)

However, since war broke out in 2011, the polio immunization rate fell from 91 percent to 33 percent. That meant that around half a million children were vulnerable to polio. The public health system was disintegrating, with over half of their medical facilities damaged, and there was a shortage of precious antibiotics and vaccines. A typhoid epidemic caused by salmonella bacteria also erupted.

In addition to polio, viral hepatitis, measles, and mumps surfaced, thought to have originated from an influx of unvaccinated Pakistani fighters into Syria. Syria itself was already hosting over 100,000 refugees from other war-torn countries. Syrians are also fleeing their country, seeking refuge in neighboring countries. There were over 4 million displaced citizens in Syria who were in need of aid.

Damage to roads and infrastructure complicated healthcare efforts to reach remote areas. A massive immunization effort was undertaken targeting the refugees and native parts of Syria that could still be reached by aid workers.

Learn more about emerging and reemerging diseases.

How War Destroys Everything 

Contagious diseases were spreading by the oral-fecal route due to contaminated water from the rivers and wells. People were drinking water straight out of the Euphrates River, which was contaminated with sewage. The situation appeared unmanageable, and the outlook was dim. In nearby countries, almost 2 million Syrian refugees took shelter in camps or host communities. 

Refugee camps on the Turkish-Syrian border began experiencing cases of cholera and malaria. Since Turkey shares a 500-mile border with Syria, it was impossible to monitor and register all refugees that were crossing the border. Some Syrians, who were sick, crossed the border and brought new diseases to areas where they were not prevalent. 

In the present times, the Syrians may continue to make their way across Turkey and into Europe, creating a further potential for the spread of diseases. The host countries are bulging at the seams, dealing with the increasing health threats to their own populations. In addition, their own resources are being diverted to the overwhelming numbers of refugees that are pouring in.

Image of Syrian refugees standing in line on railway tracks.
The Syrian civil war led to millions of refugees being forced to flee to other countries and spreading potential infectious diseases. (Image: Fishman64/Shutterstock)

This formula yields the perfect breeding ground for infectious diseases to spread at a rapid pace to contiguous countries. Wherever there’s war, this healthcare disaster scenario will continue to occur with similar themes, just at a different time and at a different place. War is a man-made disaster, but natural disasters can also have an equally devastating effect on human health.

Learn more about influenza: past and future threat.

Natural Disasters Spread Infectious Diseases Like Wildfire

Victims of a tornado in Joplin, Missouri, in 2011 suffered from mucormycosis, a rare but serious fungal infection that can start as a skin infection but disseminate throughout the body and become deadly. This happened because flying debris, containing soil contaminated with the fungus, mucor, penetrated the skin and infected wounds. 

Cutaneous mucormycosis after natural disasters is not unprecedented. In fact, 8 cases were reported after a 1985 volcanic eruption in Colombia. What about hurricanes and their public health problems? 

In the 1800s, in addition to malaria, New Orleans suffered outbreaks of cholera and typhoid fever because contaminated water was hospitable for breeding germs in the most tropical environment in the United States. Over time, an improved public health system kept epidemics at bay. But after the hurricane of 2010, several infectious diseases became problematic again.

So when we think of conditions that spread diseases after natural disasters—like crowded conditions, the lack of medical access, and the lack of clean water—we’re basically dealing with many of the same warlike conditions that affected Napoleon’s army.

Common Questions about the Spread of Infectious Diseases Across the Globe During Disasters

Q: During his campaign in Russia, how did Napoleon’s men die?

Most of Napoleon‘s soldiers didn’t obey his orders regarding sanitation and were inflicted with infectious diseases like trench fever and typhus.

Q: What makes Syrian refugees vulnerable to disease?

Many of them lost access to vaccines and medical care due to the civil war. Moreover, they are prime candidates for infectious diseases due to living in refugee camps with less than adequate hygiene and sanitary conditions.

Q: How did disease impact people during Missouri’s 2011 tornado?

Some suffered from an infectious disease called mucormycosis. This was because of flying debris containing fungus and disease reaching infected wounds.

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